Published in Am J Emerg Med 2015 Mar 33:315
Authors: Duran-Gehring PE et al.
Ultrasound can be used to visualize injected saline, localize the catheter tip, and detect pneumothorax.
Investigators compared ultrasound to chest x-ray for confirmation of placement of supradiaphragmatic central lines and to rule out pneumothorax in 46 emergency department patients. Correct placement was confirmed by visualization of microbubbles in the right atrium immediately after saline injection into the distal port. Pneumothorax was ruled out by presence of normal lung sliding.
Average time for the ultrasound exam was 5 minutes versus 28 minutes to perform the chest x-ray and 299 minutes for a radiologist’s interpretation (time to interpretation by the clinician was not reported). There were three misplaced lines and two pneumothoraces. Residents performing the ultrasound studies failed to detect two of the three misplaced lines, but subsequent over-reading by the principal investigator confirmed that the studies had shown misplacement. Resident accuracy in detecting pneumothorax was not reported.
Other small studies have shown promise for ultrasound as a replacement for chest x-ray in confirming central line placement (NEJM JW Emerg Med May 22 2014; [e-pub]and Ann Emerg Med 2014; 63:678; NEJM JW Emerg Med Dec 2009 and Crit Care Med 2009 Oct 12; [e-pub]). The present study provides further evidence that ultrasound is at least as good as, and faster than, chest x-ray. But this study also provides a cautionary lesson, because two trainees made the wrong call. Robust training for attendings and real-time supervision of trainees is necessary, but assuming these are in place, use of confirmatory chest x-rays after central line placement may soon be a thing of the past.
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